Equatorial mounts have long been used for carrying telescope optical assemblies and providing single-axis tracking of celestial objects. FIG. 1 shows a telescope 100 that includes a conventional equatorial mount 120, known in the art as a German equatorial mount. The equatorial mount 120 carries an optical assembly 110 on a cradle or clamp 130. A right ascension support 122 allows the optical assembly 110 to be rotated, e.g., on bearings 124, about a right ascension axis 126. In a similar fashion, a declination axis support 132 allows the optical assembly 110 to be rotated, e.g., on bearings 134, about a declination axis 136. A counterweight shaft 140 extends from the declination support 132, and a counterweight 142, e.g., made of steel or some other heavy material, is attached to the counterweight shaft 140.
The equatorial mount 120 sits on a base 150, which in turn sits on a support, such as a tripod 180, pedestal, or some other support. The base 150 provides a latitude adjustment 152, which allows the mount 120 to be tilted up or down, as indicated by the arrows 156, about a point 154. An operator may initially set the angle of the latitude adjustment approximately to the latitude where the telescope 100 is operated.
To enable single-axis tracking of celestial objects, the operator may perform a polar alignment of the equatorial mount 120. For example, the operator may point the right ascension axis 126 toward a celestial pole (e.g., toward Polaris in the Northern Hemisphere or toward sigma Octantis in the Southern Hemisphere), look through a polar scope 128, and vary the latitude adjustment 154 to place the celestial pole in the center of the field of view of the polar scope 128 (often designated using cross-hairs). The operator may lock the latitude adjustment at the established position.
The operator may then balance the telescope 100. For example, the operator may rotate the telescope 100 in right ascension so that the counterweight shaft 140 is parallel to the ground and then move the counterweight 142 along the shaft 140 to find a placement of the counterweight 142 that approximately balances the weight of the optical assembly 110. Balancing may be repeated if heavy eyepieces or photographic equipment are used. The operator may also balance the telescope 100 in declination, by moving the optical assembly 110 forward or back on the cradle or clamp 130. Once balanced, the equatorial mount 120 can hold any established position with minimal frictional braking and can be moved back and forth along each of its axes 126 and 136 by applying about the same amount of torque in each direction.